Waste well not a likely to produce a sinkhole, officials say

Residents close to the proposed Vanguard Environmental wastewater well in Houma should not fear it will eventually become a sinkhole like the 24-acre one in Assumption Parish, officials said.

Xerxes Wilson Staff Writer

Residents close to the proposed Vanguard Environmental wastewater well in Houma should not fear it will eventually become a sinkhole like the 24-acre one in Assumption Parish, officials said.Two weeks ago, the state Supreme Court rejected Terrebonne Parish’s appeal of a lawsuit that would have stopped Vanguard from drilling, upholding a lower court’s ruling that said the state Department of Natural Resources, not the parish, has exclusive authority to grant permits for such wells. Parish authorities and neighbors of the proposed well off New Orleans Boulevard just south of North Hollywood Road protested its proximity to local homes, schools and recreational facilities. “We certainly did not want that well where its at and we brought it all the way up to the Supreme Court,” Parish President Michel Claudet said. “Nothing is being ruled out. We’re trying to determine what options may be available with us. I can assure you on behalf of myself and the Parish Council, money is not an object. We need to do what we can do to protect our people.” Since the court ruling, some residents have suggested Houma could be threatened by a sinkhole similar to the one that opened near Bayou Corne in August 2012. That sinkhole now resembles a lake with containment levees encircling it. Though that hole, which caused the ongoing evacuation of 150 nearby families, has been tied to an injection well, it has a very different purpose and geology than the well in Houma.State officials believe the sinkhole is the result of a failed cavern hollowed out inside the subterranean salt dome beneath the area. That salt dome is a naturally occurring geological formation where solid salt thrusts up from the ancient seabed and surrounding rock. These domes are commonly used for mining of salt or storage for oil and gas. Louisiana Offshore Oil Port uses the Clovelly Dome in south Lafourche Parish to store crude deliveries from tankers in the Gulf of Mexico. Similarly, the 1-mile by 3-mile Napoleonville Salt Dome is used by multiple companies for purposes including butane storage.Texas Brine used the Assumption Parish cavern to mine highly salty water known as brine. The company injected fresh water into the dome, hallowing out a cavern and extracting the salt water for industrial uses. Over the years the cavern was hollowed thousands of feet into the dome, creating a void similar to one that would be used for storage. But unbeknownst to Texas Brine, the cavern was being hollowed too close to the dome’s edge.At some point this caused the cavern’s western wall to collapse, filling it with the earth outside. More than 3 million cubic yards of earth was displaced, causing the sinkhole. State officials note the dissimilarities between the failed brine well and cavern in Bayou Corne to the proposed injection well in Houma. The well in Houma will have high-pressure wastewater from oil and gas operations injected some 4,000 feet below the surface. The target of that well is not a salt dome but instead rock and sand formations below the surface, said Patrick Courreges, spokesman for the Department of Natural Resources, which permitted the well. In Bayou Corne, there was a removal of material that created a void in the dome, said John Griffin, professor with the Nicholls State University Department of Petroleum Engineering. But in Houma, the waste water is being pressurized in spaces between grains of sand deep below the surface — meaning there is no void that could create a similar hole. Courreges notes Vanguard has to document it will not harm any underground source of water and that there is some layer of impermeable earth above the dumping depth that would stop any waste from migrating back to the surface. This method of disposing of waste has been used for decades and is generally considered a great improvement over common practice in the 1970s and ’80s that saw much of this waste openly discharged into poorly secured containment pools or open water. Such water has been shown to contain known-carcinogens.In 1978, Congress voted to exempt such waste from a 1976 federal law that regulates the disposal of hazardous waste. As recently as 1988, the Environmental Protection Agency has explicitly held that oil and gas production wastewater should be defined as nonhazardous, regardless of whether the waste contains material that, by itself, is considered hazardous to humans or the environment. Local officials say the transport of the material to and from the well is as concerning as the well itself.

Never miss a story

Choose the plan that's right for you.
Digital access or digital and print delivery.